Section 10(a) of the Charter entitles all people "the right on arrest or detention ... to be informed promptly of the reasons therefore". It is generally expected that the arresting officer, upon making the arrest, will inform the person of the reason for the arrest. However, where the reason is obvious and the person is well aware of the reason, it is not necessary.[1]

It is not necessary to always inform the accused of the circumstances of the offence. In a murder case it is not necessary to reveal the victim's identity.[2]

The primary point of inquiry is whether the accused can reasonably be supposed to have understood the reason for the investigation.[3]

Failure to inform the accused that he is "arrested" and charged with a specific offence may not be fatal where the accused understood the basis for his apprehension and the extent of his jeopardy.[4]

To understand the extent of jeopardy it is not necessary to be aware of the precise charge face or the full extent of the details of the case.[5]

Script
The arresting officer must inform the accused of the charges and their right to counsel. Typically, the officer will read from a script such as:

I am arresting you for [name of offence(s)].

You have the right to retain and instruct counsel without delay. You also have the right to free and immediate legal advice from duty counsel by making free telephone calls to [toll-free phone number(s)] during business hours and [toll-free phone number(s)] during non-business hours.

Do you understand?

Do you wish to call a lawyer?

You also have the right to apply for legal assistance through the provincial legal aid program.

Upon arrest the peace officer should inform the accused of their right to silence and right against self-crimination protected under section 7 and section 11(c) of the Charter.

The script read to the accused will go something like the following:

POLICE WARNING:
I wish to give you the following warning: You need not say anything. You have nothing to hope from any promise or favour and nothing to fear from any threat whether or not you say anything. Anything you do or say may be used as evidence.

Where there had been previous communication between the police and accused prior to the reading of the first police warning, the police will usually provide what is called a "secondary caution" or "warning" that informs the accused that nothing said by the police prior to the first warning should influence the accused in the decision to make a statement. This is to avoid the tainting and exclusion of potential statement as "derived statements" following a previously involuntary statement.[1]

The script read is similar to the following:

SECONDARY POLICE WARNING:
I wish to give you the following warning: You must clearly understand that anything said to you previously should not influence you or make you feel compelled to say anything at this time. Whatever you felt influenced or compelled to say earlier, you are now not obliged to repeat, nor are you obliged to say anything further, but whatever you do say may be given as evidence.